Results of tests on KiwiRail's new Chinese-made locomotives for asbestos are expected today.
Forty of the state-owned company's locomotives were taken out of action following the discovery of the potentially deadly material in a soundproofing compound inside one of the vehicles on Thursday.
Samples were taken from locomotives in Auckland, Hamilton, Tauranga and Palmerston North over the weekend, and from locomotives in Wellington yesterday, KiwiRail said.
They were then analysed by an accredited laboratory in Wellington.
"Our preliminary advice following testing of a first locomotive on Friday indicted that the asbestos in that locomotive was contained and does not constitute a risk to health," KiwiRail chief executive Peter Reidy said.